The present invention relates to a method for controlling the operation of uranium enrichment systems in which the uranium is processed in the form of gaseous compounds.
Such enrichment systems, which may for example include a cascade of separating stages as shown in FIG. 4 of U.S. Pat. No. 2,951,554 issued Sept. 6th, 1960, or in FIG. 4 of U.S. Pat. No. 2,947,472 issued Aug. 2nd, 1960, serve to produce a product which is enriched in uranium 235 with respect to its natural isotope composition. In addition to other control measures, such as volume control, measurements of throughput, and chemical analyses, the degree of enrichment of the operating uranium gas should also be controlled at certain points in the system.
A number of methods are known and have been used to identify the composition of uranium isotope mixtures. The method most commonly used is mass spectrometry. However, it is noted that mass spectrometers are very sensitive instruments which can be operated only by qualified personnel and are not suitable for routine monitoring.
The use of spectrometry, i.e., gamma spectrometry, for determining uranium content is fully outlined and described in various sources of literature such as in C. E. Crouthamel, APPLIED GAMMA-RAY SPECTROMETRY, 2nd edition, page 648, Pergamon Press, 1970; J. Wolff, "Einige Anwendungsmoeglichkeiten der Hochaufloesenden Gamma-Spektroskopie zur Spaltstoffbestimmung", [Several Possible Ways of Using the Highly Resolving Gamma-Spectroscopy for the Determination of Fission Products], Gesellschaft fuer Kernforschung, Karlsruhe, Germany, external report 4/71-33, Mar. 1971 (Institute for Neutron Physics and Reactor Art).